An Efficient Probabilistic Context-Free Parsing Algorithm that Computes Prefix Probabilities

We describe an extension of Earley's parser for stochastic context-free grammars that computes the following quantities given a stochastic context-free grammar and an input string: a) probabilities of successive prefixes being generated by the grammar; b) probabilities of substrings being generated by the nonterminals, including the entire string being generated by the grammar; c) most likely (Viterbi) parse of the string; d) posterior expected number of applications of each grammar production, as required for reestimating rule probabilities. (a) and (b) are computed incrementally in a single left-to-right pass over the input. Our algorithm compares favorably to standard bottom-up parsing methods for SCFGs in that it works efficiently on sparse grammars by making use of Earley's top-down control structure. It can process any context-free rule format without conversion to some normal form, and combines computations for (a) through (d) in a single algorithm. Finally, the algorithm has simple extensions for processing partially bracketed inputs, and for finding partial parses and their likelihoods on ungrammatical inputs.Comment: 45 pages. Slightly shortened version to appear in Computational Linguistics 2

Precise n-gram Probabilities from Stochastic Context-free Grammars

We present an algorithm for computing n-gram probabilities from stochastic context-free grammars, a procedure that can alleviate some of the standard problems associated with n-grams (estimation from sparse data, lack of linguistic structure, among others). The method operates via the computation of substring expectations, which in turn is accomplished by solving systems of linear equations derived from the grammar. We discuss efficient implementation of the algorithm and report our practical experience with it.Comment: 12 pages, to appear in ACL-9

Comparing Human and Machine Errors in Conversational Speech Transcription

Recent work in automatic recognition of conversational telephone speech (CTS) has achieved accuracy levels comparable to human transcribers, although there is some debate how to precisely quantify human performance on this task, using the NIST 2000 CTS evaluation set. This raises the question what systematic differences, if any, may be found differentiating human from machine transcription errors. In this paper we approach this question by comparing the output of our most accurate CTS recognition system to that of a standard speech transcription vendor pipeline. We find that the most frequent substitution, deletion and insertion error types of both outputs show a high degree of overlap. The only notable exception is that the automatic recognizer tends to confuse filled pauses ("uh") and backchannel acknowledgments ("uhhuh"). Humans tend not to make this error, presumably due to the distinctive and opposing pragmatic functions attached to these words. Furthermore, we quantify the correlation between human and machine errors at the speaker level, and investigate the effect of speaker overlap between training and test data. Finally, we report on an informal "Turing test" asking humans to discriminate between automatic and human transcription error cases

El lloc de les dones fora de lloc

Aquest assaig tracta de la doble exclusió politico-econòmica que viuen les dones immigrants, per una banda com a "persones fora de lloc" i, per una altra, com a dones generalment pobres. En la primera part analitzo els termes en què es racionalitza la creixent hostilitat i el refús als immigrants extracomunitaris. Els polítics i els mitjans de comunicació hostils a la immigració extracomunitària fan menció especial a l'amenaça que significa la "invasió" des del sud per a la identitat cultural i els recursos "nacionals", i atribueixen el fet de la immigració a la "bomba demogràfica" existent en el paisos d'origen. És a dir, el "problema" està en els "altres" i no en "nosaltres". Les retòriques alarmistes demogràfiques -antinatalistes per al sud i natalistes per al pròsper però envellit nord-, juntament amb el fonamentalisme cultural de les retòriques antiimmigrants, tenen dues conseqüències. Per una banda, emmascaren les arrels reals de la pobresa del Tercer Món i, per una altra, porten a un control agressiu de la procreació de les dones en els seus països d'origen. Aquelles que migren estan, a més, sotmeses a una segona culturalització discriminatòria. Tal com es veurà, són confinades als estrets espais socioeconòmics tradicionalment femenins a Occident per ser immigrants pobres i a més dones. Així, són discriminades per ser estrangeres indesitjables i, a més, per ser dones.Este ensayo trata de la doble exclusión politico-económica que viven las mujeres inmi- grantes, por un lado como apersonas fuera de lugarn y, por otro, como mujeres general- mente pobres. En la primera parte analizo los términos en que se racionaliza la creciente hostilidad y el rechazo de los inmigrantes extracomunitarios. Los políticos y medios de comunicación hostiles a la inmigración extracomunitaria hacen hincapié en la amenaza que significa la ainvasiónr desde el sur para la identidad cultural y los recursos "nacionales", y atribuyen el hecho de la migración a la abomba demográficas en los paises de origen. Es decir, el "problema" está en los "otros" y no en "nosotros". Las retóricas alarmistas demográficas -antinatalistas para el sur y natalistas para el próspero pero envejecido norte-, junto con el fundamentalismo cultural de las retóricas antiinmigrantes, tienen dos consecuencias. Por una parte, enmascaran las raíces reales de la pobreza en el Tercer Mundo y, por otra, redundan en un control agresivo de la procreación de las mujeres en sus paises de origen. Aquellas que migran están, además, sometidas a una segunda "culturalización" discriminatoria. Como muestro, se ven confinadas a los estrechos espacios socioeconómicos tradicionalmente femeninos en Occidente por ser inmigrantes pobres y además mujeres. Así, son discriminadas por ser extranjeras indeseables y, además, por ser mujeres.Cet essai traite de la double exclusion politico-économique que vivent les femmes immigrantes, d'un coté comme "personne hors place" et, de l'autre, comme femmes généralement pauvres. Dans la première partie, j'analyse les termes qui servent à rationaliser la croissante hostilité et le rejet envers les immigrants extra-communautaires. Les politiques et les moyens de communication hostiles à l'immigration extra-communautaire insistent sur la menace que signifie "l'invasion" du sud pour l'identité culturelle et les ressources "nationales" et attribuent le fait de la migration à la "bombe démographique" que constituent les pays d'origine. C'est à dire que le "problème" est dans les "autres" et non en "nous". Les discours démographiques alarmistes - anti-natalistes pour le Sud et natalistes pour le Nord prospère mais vieux-et le fondamentalisme culturel des réthoriques anti-immigrants ont deux conséquences. D'un coté, ils masquent les racines réelles de la pauvreté dans le Tiers Monde et, d'autre part, ils insistent sur un contrôle agressif de la procréation des femmes dans leurs pays d'origine. Celles qui migrent sont, en plus, soumises à une segonde "culturalisation" discriminatoire. Pour être immigrantes pauvres et femmes, elles sont confinées dans les espaces socio-économiques étroits traditionnellement féminins en Occident. Ainsi, ces femmes sont discriminées pour être des étrangères indésirables et, de plus, pour être femmes.This essay deals with the double -politica1 and economic- exclusion which immigrant women suffer, on the one hand as "out-of-place people" and, on the other, as mostly poor women. The first part offers an analysis the circumstances in which the growing hostility towards and the rejection of non-Community immigrants are rationalized. Those politicians and mass media who are hostile to non-Community immigration insist on the threat which this Southern "invasion" represents for "national" cultural identity and resources, and attribute migration to the "demographic boom" in the countries of origin. In other words, the "problem" is "theirs", not "ours". Alarmist demographic rhetoric -anti-natalistic for the South and natalistic for the prosperous but aged North- together with the cultural fundamentalism of anti-immigrant rhetoric has two consequences. In the first place, they disguise the true roots of Third World poverty and, in second place, redound on the agressive control of female reproduction in the countries of origin. Those women who migrate are, moreover, subjected to a second discriminatory "culturalization". The article demonstrates that in the Western world they find themselves confined to narrow, traditionally female socio-economic space as a result of being poor immigrants and, on top of this, women. These women, therefore, suffer discrimination as undesirable foreigners and as women

A propósito del sexo

Sex together with death are probably the most intensely and diversely symbolized events in human experience. Recent changes in Western sexual mores transcend, nonetheless, the socio-cultural realm. Embryological research and biotechnological experimentation have brought about transformations in the facts of life and the nature of sex which were hitherto inconceivable. In this article I analyze the state of cloning with the aim of thematizing two related issues. Biotechnology is especially good for thinking because it challenges conventional modern dualism which dissociates nature from culture. And a proper comprehension of the implications these biotechnological innovations may have for our conventional notions of reproduction, kinship and sex/gender relationships requires that, beyond analysing its symbolic meanings, we take the materiality of sex seriously.El sexo junto con la muerte son seguramente los momentos de la experiencia humana más intensa y diversamente simbolizados. Los cambios que han tenido lugar en los usos y costumbres sexuales en décadas recientes en las sociedades occidentales trascienden, no obstante, el ámbito socio-cultural. La investigación embriológica y la experimentación biotecnológica han introducido transformaciones aún hace poco inconcebibles de los hechos de la vida y en especial en la naturaleza del sexo. En este texto analizo la actualidad de la clonación para plantear dos cuestiones relacionadas. La biotecnología es tan buena para pensar pues desafía el dualismo convencional moderno que disocia la naturaleza de la cultura. Y para comprender las implicaciones de los avances biotecnológicas para nuestras nociones convencionales de la reproducción, del parentesco y de las relaciones de sexo/género es preciso tomar en serio mas allá de sus significados simbólicos, las materialidades del sexo

Advances in All-Neural Speech Recognition

This paper advances the design of CTC-based all-neural (or end-to-end) speech recognizers. We propose a novel symbol inventory, and a novel iterated-CTC method in which a second system is used to transform a noisy initial output into a cleaner version. We present a number of stabilization and initialization methods we have found useful in training these networks. We evaluate our system on the commonly used NIST 2000 conversational telephony test set, and significantly exceed the previously published performance of similar systems, both with and without the use of an external language model and decoding technology